閉鎖型養液栽培におけるスギ樹皮培地の連用が培地の理化学性およびトマト収量に及ぼす影響(栽培管理・作型)  [in Japanese] Physiological and Chemical Ageing of Cedar Bark Substrate and Their Effects on Tomato Yield in a Closed Hydroponics System(Crop Production & Cropping Type)  [in Japanese]

毛管給液を併用した閉鎖型養液栽培システムにおいて,トマトを促成栽培した年数の異なるスギ樹皮培地の理化学性,培地内溶液の成分濃度,トマトの生育および収量について検討した.スギ樹皮培地の三相分布では,液相率および気相率は連用しても変化しなかったが,固相率は連用年数の増加にしたがい低下した.十分に湛水した培地を本システム上に設置した後の培地重量の変化は,連用年数が多いほど小さかった.連用年数の増加によりCECは高くなり,窒素の取り込みは少なくなった.また,培地内溶液のNO_3-N濃度は連用年数が多くなるにつれ高く推移する傾向で,K,Ca,Mg濃度は3年区までに比べ5年区で高く推移した.茎径は1年区の第1,3花房で小さかった以外は連用による差はなかった.収量は2年区で高い傾向にあり,その後は連用により低下し,5年区では2年区と比べて有意に少なかった.本実験により,連用年数の違いによるスギ樹皮培地の理化学性の変化,収量などが明らかとなり,本システムにおけるスギ樹皮培地は5年連用後に交換するとよいことが示唆された.

Tomatoes were grown on substrates made of cedar bark to investigate the effects of decomposition changes in physiological and chemical properties of substrates, the concentrations of the components in the solution within the substrates, and the growth and yield of tomatoes. The substrates were fixed in a closed hydroponic system with a capillary uptake method. The liquid and gaseous phases of the substrates did not differ, while the solid phase decreased as decomposition proceeded. As decomposition progressed, the annual weight loss in the substrates grew smaller, CEC of the substrates increased, nitrogen absorption by the substrates decreased, and the NO_3-N level in the solution within the substrates tended to fluctuate higher. K, Ca, Mg levels in the solution within the substrates were higher in substrate used for five years than in substrates used less than three years. There were no difference in stem diameter of tomato plants at the first and third clusters, except that plants showed thinner stems on the one-year-old substrate. The yield of tomato fruits tended to be higher on two-year-old substrate than on one-year-old substrate. The yield was lowest on the five-year-old substrate. It was suggested that the substrate be replaced after five years.